Described herein is a system and method using same for storing and delivering a process chemical or chemical precursor, such as a high purity, liquid chemical precursor, to a process tool that is used in the manufacture of a semiconductor device. More specifically, described herein is a system comprising a container (a vessel or an ampoule), and chemical precursors for a process tool such as a deposition reactor in a chemical vapor deposition (CVD) or atomic layer deposition (ALD) process.
Semiconductor manufacturing processes involve the use of high purity, chemical reagent(s) or liquid chemical precursors that are delivered to a reactor and used to deposit a material on a substrate. These chemical precursors are typically contained in sealed containers to protect against contamination of the precursors and to prevent leakage. Precursors used in CVD or ALD processes are routinely delivered to the reactor by evaporating them into a carrier gas that is passed through a container of the chemical. Some of these precursors which are used in the manufacture of semiconductors exhibit low vapor pressure (less than about 50 Torr-absolute at delivery temperature).
The Containers for delivering those liquid precursors typically inject the incoming carrier gas below the surface of the liquid, creating a so-called ‘bubbler’ design, as disclosed in U.S. Pat. No. 8,313,804 B2 and U.S. Pat. No. 6,033,479 A. Injection of the gas below the surface causes the gas to form bubbles that rise through the liquid before bursting on the surface, releasing the gas to travel as a vapor to the outlet of the container. Bubbling the gas through the liquid is an effective means of creating greater gas-liquid contact time and area, which aids in achieving a gas stream that is saturated with the evaporated liquid precursor. Achieving saturated carrier gas maximizes the delivery rate of the precursor and is generally beneficial to the operation of the deposition process. The use of a bubbler design is most beneficial for low vapor pressure precursors, such as those with vapor pressure less than about 50 Torr-absolute, which require the use of a carrier gas.
However, some liquid precursors may either contain solid particulates or form solid particulates over time through a chemical change (decomposition). For such materials, the bursting of bubbles at the surface of the liquid in a bubbler-style container can lead to the formation of aerosols and/or mists. These aerosols or mists can become entrained in the carrier gas flow and transport solids or dissolved solids to the outlet of the container. At the outlet of the container, such solids or dissolved solids may accumulate in the outlet valves or other locations downstream of the container. Deposition of these solid materials can cause plugging, flow restrictions, and other undesirable phenomena.
Thus, such a bubbler container design is unsuitable for materials that may contain or form solid particulates, since such particulates could become lodged in the outlet valve or any downstream process section.
U.S. Pat. No. 5,589,110 (“the '110 Patent”) describes metal organic compound container apparatus for containing a liquid metal organic compound, receiving a carrier gas, and producing a carrier gas stream saturated with vapor of the metal organic compound including a container for containing a liquid metal organic compound; an inlet pipe for introducing a carrier gas into the container, the inlet pipe having an end for immersion in the metal organic compound; a carrier gas flow rate controller for controlling carrier gas flow into the inlet pipe; a first exhaust pipe for exhausting carrier gas from the container at a first flow rate, the first exhaust pipe having an end not contacting the metal organic compound; a first gas flow rate controller for controlling one of pressure and the first flow rate of the carrier gas through the first exhaust pipe; a second exhaust pipe for exhausting carrier gas from the container at a second flow rate, the second exhaust pipe having an end not contacting the metal organic compound; and a second gas flow rate controller for controlling the second flow rate. In one embodiment of the '110 Patent, the container comprises adjusting pipes that “slidably provided at respective ends of said inlet pipe and said exhaust pipe for position of the inlet and the exhaust pipe above and spaced from a surface of a metal organic compound in said container” and “including a float attached to said adjusting pipes for floating in a metal organic compound in said container, thereby maintaining said adjusting pipes spaced from the metal organic compound in said container.”
The inlet pipes and floats can be moving during use to compensate for the reduced mass transfer that occurs as the distance between the inlet pipe and liquid surface increases. This problem is particularly acute with the low carrier gas flow rates specifically addressed in the '110 patent.
However, moving inlet pipes and floats can cause some complications, particularly if the liquid precursor contains solids or dissolved solids. The inlet pipes and floats can become stuck during use by deposition of the solids in the sliding mechanism, and are difficult to clean after use.
There is a need in the art for a system and a method to contain and deliver liquid process chemical(s) or chemical precursors that may contain or form solid particulates that reduces one or more of the following problems: plugging, flow restriction, insufficient saturation of precursor in the carrier gas, drop off in saturation, ease of manufacture, and/or ability to be thoroughly cleaned after use.